Engines

Manufacturer installed stall prevention systems

1)variable inlet guide vane and stator vane. Positioned into place using fuel pressure from fuel control unit. This action maintained velocity of the air. 2) Dual/twin/split-spool compressor— allows front rotor to turn slower than rear rotor. Front rotor can turn without being chocked by low airflow. 3)bleed valves— installed near middle or rear of compressor to bleed air and increase airflow in the front of the compressor at lower engine RPM. 4) variable exhaust nozzle. Used to unload pressure during afterburner operation. (Or else back pressure.)

Remember that 75 percent of heat energy from the burner is used to drive the compressor and accessories. Other 25 percent is for thrust. Percent of thrust comes from exhaust on turboprop?

10% of the 25% other 90% comes from air being displaced by rotor.

Current axial flow compressors have a near ——- % efficiency and compression ratios approaching ———. Several high Performance engines have 25:1 ratios. Remember that simple centrifugal compressors can only attain compression ratios between 6:1 and 7:1.

90 & 15:1

The compressor is not

A closed system

Turboprop engine build

A gas generator coupled with a reduction gearbox and propeller, driven by the turbine section. The propeller imparts a small amount of acceleration to a large mass of air.

Axial Flow Compressor

A type of compressor used in a turbine engine in which the airflow through the compressor is essentially straight. An axial-flow compressor is made up of several stages of alternate rotors (rotating) and stators(stationary). The compressor ratio is determined by the decrease in area of the succeeding stages.

Centrifugal compressor Ad/Disadv

ADVANTAGE Rugged/low cost/ good power output over a wide range of RPMs/high pressure increase per stage. DISADVANTAGE large frontal area required/ impractical for multiple stages.

Axial flow compressor Dis/advantages

ADVANTAGES High Peak efficiencies Small frontal area reduces drag Straight through flow- for high ram efficiency. Combustion efficiency than centrifugal compressor With dual/twin/split spool, starting flexibility better and it has improved performance at altitude. DISADVANTAGES At low inlet speeds airflow will decrease in compressor creating a high AOA. Good efficiencies only available over narrow rotational-speed. High starting power requirements Cost and difficulty in manu. High speed aircraft may experience an inlet air temp of 250 deg Fahrenheit due to ram effect. The high compressor temps cause low compression ratios an also reduce air supply to the rear of the compressor.

Characteristics of turboprop

ADVANTAGES Develops very high thrust at low airspeeds Excellent take off, slow speed & altitude traits Superior for lifting heavy loads off short runways.

He compressor is designed to provide the optimum ratio. This ratio is formed by optimizing the AOA for each stage of the compressor. If the

AOA is too low then the combustion ratio is less and the compressor will be inefficient. If too high then risk potential stall.

Instances where airflow distortion may induce compressor stall

Abrupt change in attitude Encountering air turbulence Deficiency of air velocity or volume Rapid throttle movement

Turbofan over turbojet?

Advantages: higher thrust at low airspeeds (fan) Lower TSFC shorter takeoff distance Considerable noise reduction DISADVANTAGES Higher specific weight Larger frontal area Inefficient at higher altitudes. (Fan is not fast enough relative to surroundings at high airspeed

The diffuser is located ———- the compressor, and it prepares the airflow for the ————. Reason for existence?

After & burner chamber. The velocity must be decreases to avoid blowing out the burner flame and the increase in pressure helps combustion and fuel efficiency.

At supersonic air speeds

Air becomes compressible.

Most common cause of a compressor stall?

Airflow distortion — resulting from aircraft attitude and airspeed. At High AOA, air entering inlet is slower and turbulent.

flame holder

Allow for proper mixing of fuel and air for combustion. These flame holders usually take the shape of several concentric rings with a V cross-sectional shape.

Divided-entrance inlet duct

Allows the pilot to sit lower in the fuselage and reduces friction losses due to length. However, it does distort some incoming air from boundary layer air and skin friction. It also increases drag, and could cause turbulence.

Turbo prop engine has two ranges of operation.

Alpha — flight range— PCL put from zero — full Beta -ground ops — PCL put from full reverse to full forward.

Gas generator mean?

An engine which is operated by converting energy of expanding gases into propulsive force.

Diffuser

An opening which shape decreases velocity and increases the pressure of an airflow

nozzle

An opening whose shape increases the air flows velocity and decreases the air flows pressure.

Axial flow compressor unfortunately

Axial flow compressor has delicate blades (especially in the rear) making it susceptible to FOD. The thousands of rotor/stray or blades make it expensive also.

In subsonic flight air is incompressible, therefore subsonic airflow will act according to

Bernoullis theorem. V1P1=V2P2

Prop assembly made of

Blades, hub, and pitch change/dome assembly. Blades go into the hub and hub onto prop shaft.

Inlet design must also minimize intake amount of

Boundary layer air. (Dead still air on surface of airframe.)

Three general types of combustion chambers use today?

Can(used on older centrifugal compressor engines) annular(smaller aircraft/helicopter where engine removal is easier) can-annular(used on larger, high performance engines)

Centrifugal flow compressor consists of three main components. Air enters this type of compressor near the ——- of the impellar. This high rotational speed increases airflow velocity. As the air is accelerated outward is passes through ——- passages on the impeller causing a pressure increase. Since the airflow velo & pressure is increased by the impeller —— increases. As airflow is thrown from the outer rim of impeller it is forced through divergent passages in the diffuser. The diffuser is stationary and does not add energy to airflow. Those divergent passages in diffuser convert high velo air into high pressure. Airflow then passes through the compressor ——- which directs airflow into combustion chamber

Center / divergent / total pressure / compressor manifold. IMPELLAR (aka the rotor inducer) -driven at high speeds by the turbine accelerates the air outward toward the diffuser. DIFFUSER -converts high velo to high pressure airflow MANIFOLD — directs airflow to the combustion chamber.

3 types of compressors used in construction of gas turbines

Centrifugal, axial, axial-centrifugal flow compressors

On all gas turbine engines it will minimally included

Compressor, combustion chamber, turbine.

Supersonic inlet further explained

Convergent at front, then supersonic airflow enters, is slowed down and has pressure increase, now it's subsonic but still to fast for compressor, so it's divergent (but for subsonic) increasing pressure further, and further decreasing velocity.

Supersonic inlet shape. Why?

Convergent then divergent.

Characteristics of turbojet

DISADVANTAGES low propulsive efficiency at low air speeds Relatively high TSFC at low alt and airspeed Long takeoff roll required. ADVANTAGES lightest specific weight (weight per pound of thrust produced) Higher and faster than any other engine. Best suited for high speed high altitude flight

The burner section contains the combustion chamber and provides the means for proper mixing of fuel and air for good combustion. It must

Deliver the combustion gases to turbine section at temperature that won't exceed turbine blades limits (metallurgy) and add sufficient heat to the gases to accelerate their mass and produce desired thrust.

A supersonic nozzle is ———— and a subsonic nozzle is ————-?

Divergent & convergent

Airflow from compressor entering burner section is

Divided into two types: primary & secondary. Primary is 25% and mixed with fuel for combustion Secondary is 75% and flows around the chamber through small holds to cool the thin walls and control the flame. This I burned air can also cool the turbine and be used for afterburner operation.

Factors affecting thrust of a gas turbine

Engine RPM, airspeed, air density

Exhaust section made up of

Exhaust outer duct, exhaust inner cone, radial hollow struts (for structural stability and to straighten swirling gases from turbine section.)

On a turbo fan/prop/shaft. Minimally included is

Fan, propeller, rotor blades

The duct area for afterburner operations is larger than normal exhaust duct in order to obtain a reduced velocity gas stream, this reducing gas friction loss. This reduced velocity is still too high for stable combustion, therefore it is necessary to use a form of flame stabilization or ??

Flame holder. Located downstream of the fuel spray bars. The flame holder provides a region in which airflow velocity is reduced and turbulent eddies are formed.

In turbine engine, pressure changes, temp changes and pressure changes creat thrust.

From intake to exhaust the pressure does not have a net change, the temperature is higher, as is the velocity.

Axial centrifugal flow compressor. This compressor uses ———- in addition to rotors and stators.

GUIDE VANES Inlet guide vanes impart a swirling motion to air entering the compressor in direction of engine rotation. Improving aerodynamic characteristics of compressor by reducing drag on first stage rotor blades. Exit guide vanes known as straightening vanes are located at the discharge end of compressor. They are last set of stator vanes, preparing airflow for diffuser by straightening it, reducing turbulence as it comes off the rotational movement of the compressor.

A —————— produces the high energy airflow necessary for thrust

Gas generator

Brayton cycle all take places throughout the ————. While the Otto cycle will take place within a single piston.

Gas turbine engine

Turbo shaft is similar to turbo prop except..? They are used for? Components are?

He turbine is turning something other than a prop. Like a helicopter rotor. Components are gas engine and free/power turbine. Mechanically independent, The gas generator exhaust drives the power turbine. Power turbine connected to reduction gear box through a coaxial main drive shaft. The main drive shaft can be located on the rear or front of engines.

Turbo jet at low airspeed is very wasteful because of the turbojets airflow being low mass, high velocity. Compared to a turbo prop ————— which is much more efficient.

High mass and low velocity airflow

Turbojet has the best —— and worst/——— ———-?

High speed and altitude performance. Worst/longest takeoff roll

Most fuel efficient engines are those with ———- bypass ratios

Higher

The ——- the temperature the turbine section can bear the —— the thrust produced.

Higher and higher A turbine inlet temperature increase of less than 50% will increase thrust about 130%.

Airspeeds affect on thrust

If mass and air density remain the same then thrust will decrease at higher airspeed

Fans are driven by either a free or power turbine, or through the gas generator turbine.

In either case the gas generator turbine will extract 75% of total energy just to turn the compressor and accessories.

After burning or thrust augmentation is a method used

In turbojets or turbofans to increase maximum thrust available from an engine by 50%, however this comes at up to 300% increased fuel consumption.

At higher rates of revolution an increase in throttle will ————— and at low rates of rev an increase in throttle will ———.

Increase large amount of thrust & low amount of thrust. (Inertia/shaft efficiency)

Basic law of aerodynamics states that the SOS ——- as air temp increases. Air temp is increased in compression phase, the high pressure compressor can attain higher speeds without exceeding the SOS. Also the blades of the high pressure compressor or shorter than low pressure compressor, turning faster before exceeding their limiting Mach number.

Increases. With regards to dual axial flow compressors

Turbojet constructed of ?

Inlet, compressor, burner, turbine, exhaust nozzle.

screech is characterized by loud noise and vibration. Violent pressure fluctuations caused by cyclic vibrations. To control

Install inner sleeves known as screech liners. Corrugated and perforated with thousands of holes that allow the liner to reduce pressure fluctuations and vibrations. Acting as shock absorber.

Turbo fan can lift larger weights and has shorter takeoff distance but means that

It has a larger frontal area and increases drag.

can combustion chamber disadvantages

It's advantage of ease of maintenance is a double edged sword. Inefficient use of space and the possibility that if one fails then the turbine section will have non uniform temperature distribution. (Since each can directly adjoins the turbine section.

Inlet duct

Job is to provide high pressure, turbulence free air to the compressor.

Reduction Gearbox

Located between prop assembly and gas generator, basically a one speed transmission. This assembly prevents prop blades from reaching supersonic speeds. Prop blades are meant to push subsonic air. If blade tips reach supersonic they would slip through the compressible supersonic airstream.

Thrust equation has two variables, what are they? Think Ram affect.

Mass of air and acceleration or speed of inlet air vs exhaust air.

ram effect

Mass of airflow in middle is increased greatly as air become compressible. A small benefit still arrived from subsonic airflow.

The purpose of the exhaust duct is to

Maximize the increase in velocity at the expense of pressure.

Criteria considered when designing a burner section

Minimize pressure decrease through the burner (avoid a stall) Combustion efficiency must remain high Flame must not blow out All burning must be complete before gases enter the turbine section. (Energy would be wasted if gases continued burning through the turbines. Damage could also occur)

Criteria for a good burner section.

Minimum pressure loss. High combustion efficiency Flame must not blow out Contain the total combustion process.

Fighters (f15/18) are designed with a low bypass design. Making them

More efficient than a turbojet although their is more airflow through the gas generator, producing more thrust at higher speeds.

According to the thrust equation, if of an airflow mass increases then the thrust will increase. Denser air results in more airflow mass,

More thrust is created from airflow that is dense. (Lower temp, altitude, dry cold)

Electric Starter

Most common type used on small gas turbine engines. Connected manually to the compressor, mounted either on the engine accessory gearbox or the front frame of the engine.

The T-6B has a starter generator,

Mounted on the engine accessory gearbox able to function as either starter or generator.

Two types of exhaust ——-! The

Nozzles! What is a nozzles job again? What is diffusers job? The convergent type and convergent-divergent type. Both are meant to act as nozzles. One is for subsonic and the other or supersonic. Guess which?

Turbofan has a reduction from the high end airspeed because

Of the large mass of airflow from the fans that are only accelerated to moderate speeds. On a high bypass turbofan the primary air could be less than 25%. At high altitude would greatly reduce this airflow mass.

On a forward fan design the fan blades look similar to rotor blades of the compressor that have been enlarged. The cross section of the fan is larger than the front area of the compressor, allowing a relatively large mass of air to bypass the gas generator.

On average this mad of bypassed air can produce between 30-60% of total turbofan thrust. The gas generator providing 30-70% of thrust.

Brayton Cycle

Operating cycle consisting of four events which occur simultaneously, intake, compression, combustion, exhaust This op cycle is different from op cycle of a piston engine.

Thrust measuring instruments

PRESSURE INDICATION GUAGES turbojets, turbofans, use a Engine Pressure Ration Gauge. (Ratio of inlet to exhaust airflow.) Torquemeter— prop driven craft use. Indicate PA using shaft horsepower. Tachometer— not a measure of thrust but an assessment of energy production. Uses percentages rather than high RPM numbers.

For shorthand static pressure is referred to as ———— and dynamic pressure is referred to as ——-

Pressure & velocity

Multistage axial compressor vs centrifugal flow compressor.

Pressure gains per stage not as great, but the efficient use of multiple stages can produce high overall compression ratios.

Thrust that a gas turbine engine develops is essentially the result of many changes in

Pressure temperature and velocity as the air flow passes through the engine.

Together these systems establish the correct combination of RPM, fuel flow, and blade angle to create the thrust required.

Propeller governor & turboprop engine fuel control unit.

Torquemeter assembly operating on the principle of accurately measuring the power transmitting along the torque shaft.

Provides front engine mount and transmit engine output power to the PRGBs. The power is measured electromagnetically as twisting of the torque shaft.

Turbofan is ———— because of the generated thrust from the fans and not just the burner combustion.

Quieter

Signs of compressor stall

RPM Drop, rise in turbine temperature, loud bangs, engine vibrations.

Since a compressor stall results in loss of airflow to turbines, mor fuel is required for same thrust. Signs of stall result as

RPM decay, mild pulsation, interstage turbine temperature (ITT) rises.

Multiple-Stage Axial flow compressor

Rotors are driven by a turbine, which increase velocity and pressure of incoming airflow (not closed system) thus increasing total pressure. Simply- the air is pushed through the stator veins which act as diffusers, decreasing velo and inc pressure. Then airflow passes onto next rotor/stator stage. Stall area (chapter 3) will be approached if velocity is not decreases gradually then it will halt at the end.

How does am afterburner work

Secondary air from the burner along with bypassed air (turbofan) is mixed with fuel and ignited in the afterburner duct to augment thrust.

———— from the burner section is used in the afterburner section. The ignition of this air mixed with fuel results in a large ——————-?

Secondary air. Temperature rise and a great acceleration of gases.

A reciprocal engines cycle is like that of an automobile, called the Otto cycle. Unlike brayton cycle, Events are happening ——— rather than ———-.

Sequentially rather than simultaneously

Turbines like compressors May be..? A dual spool compressor requires...?

Single of multistage. Dual turbines driving Te cores does via separate shafts.

Centrifugal flow compressors May be utilized in multiple configurations.

Single stage, multi stage, and dual faced

Percentage of thrust production dependent on

Size of fan, turbine arrangements, atmospheric conditions.

Why are reduction gearboxes required for a turboprop?

So the blade tips are kept subsonic and don't slip through the air ineffectively. Turns high RPM low torque to low rpm and high torque.

For basic afterburner parts (four)

Spray bars(introduce fuel to afterburner) some are on off and others are variable. , flame holders( , screech liner( , variable exhaust nozzle(

Turbine section like the compressor is comprised of ——— & ——— & drives the ———. It also is meant to increase ——-.

Stators & rotors & Compressor and accessories. airflow velocity.

Can-annular combustion chamber benefits and drawbacks $$$$

Stronger structural stability of can burner but less loss in pressure. Ease of maintenance while simultaneously providing even distribution of temperature at turbine inlet.

Primary function of compressor is to

Supply enough air to satisfy the requirements of the combustion section. Specifically, the comp increases pressure of airflow from inlet duct and directs it to burner in the quantity and pressure required.

T-6B compressor uses a four-stage axial compressor and one centrifugal impeller to compress the air.

T-6B compressor uses a four-stage axial compressor and one centrifugal impeller to compress the air. The air moves forward from the compressor through different diffuser tubes where velocity is converted into pressure.

T=ma

T=ma

The T-6 RGB reduces power turbine output shaft speed of over 30000 RPM to the prop operating speed of 2000RPM.

The RGB is mounted on the front of the engine and driven by the hot gases impinging on the two stage power turbine.

Bypass ratio

The amount of air that bypasses the gas generator in comparison with the amount of air that passes through the gas generator.

Disadvantages of annular combustion chamber

The annular combustion chambers uniform heat distribution is double edged. From this benefit there lies the problem that if there is an issue you must remove the entire unit, whereas on the can system you could simply take off a single can.

Axial-centrifugal flow compressor

The axial section allows for straight through ram efficiency, and multiple stages for high pressure. The centrifugal section increases that pressure through its one stage. The small cross section of the centrifugal section keeps the engine relatively small.

For the T-6

The diffused air passes through straightening vanes prior to reaching the annulus surrounding the combustion chamber. The air is mixed with fuel and ignited inside the combustion chamber. The resultant expanding gases drive the SINGLE STAGE gas generator turbine, which shares a common shaft to drive the compressor impellers. The gases the impinge on the two stage power turbine, driving the reduction gearbox. Exhaust gas flows out sideways then is rejected rearward from the exhaust stacks, augmenting thrust produced by the prop.

Within the compressor a stalls causes are similar to that of an air wing.

The relative wind is formed by combining compressor rotation (RPM) and inlet air flow. The angle between this relative wind and rotor blade chord line make up the AOA. Relative wind forms a 45 degree angle (think) and the chord line is slightly negative on most rotors. (So can produce lift while gradually diving.) So the AOA is just greater than 45 degrees.

Even though the rotor blades are installed on the rotor disk, the AOA can still change

The relative wind vector — therefore the AOA — changes depending on the RPM's or the speed of inlet airflow (aircraft speed). Decrease inlet airflow or increase RPM's. Deploying drag devices. Changing AO away from L/Dmax. Or revving engine.

High compression ratios are desirable because?

The same combustion temperature can be reached with less fuel, while giving longer expansion cycle, creating more mechanical power output

Supersonic Inlet Duct May produce a vibration or buzz sound, caused by?

The shock wave rapidly being swallowed and expelled at the inlet of the duct. The supersonic inlet is convergent then divergent, this acts as a buffer for any turbulence that could damage the face of the compressor.

The turbine (made of stators & rotors) rotor section converts the heat energy (potential & kinetic) of the hot expanding gases from burner chamber into mechanics energy. About 75% of total pressure from exhaust gas is converted. The exact amount of absorption in the turbine is determined by the load the turbine is driving (remember the turbine drives the compressor). What determines turbine load?? The extra 25% of available energy is used for??

The size of compressor, type of compressor, and accessories. Thrust.

Purpose of the turbine section is to?

The the compressor and accessories.

Turbofan vs turbojet. At same fuel consumption rate

The thrust is greater from a turbofan. The fan moves air through which aids in the turbine rotation. Turbofan has a lower TSFC

Supersonic air acts opposite to Bernoulli's equation. When going through a convergent openinf

The velocity (dynamic pressure) decreases and the pressure (status pressure) increases. The RAM effect

If an aircrafts speed equals its exhaust velocity.

Then one hundred percent propulsive efficiency would be reached.

Importance of inlet Guide vanes?

They rotate same direction as engine, improving aerodynamic properties of the compressor. Less drag on the first turbine of engine.

Turkey feathers are

This metal plates that can be open or closed for either supers or subsonic operation. A variable exhaust nozzle ca open to allow the supersonic gases to expand at the proper rate. Preventing gases from backing up and creating an engine stall. Supersonic has to flow!!!

Inlet valves are designed to ————-. Designed to be a straight and smooth as possible to avoid friction along inlet surfaces and pressure fluctuations. Also to reduce

To be a diffuser, never a nozzle. Designed with consideration to reduce friction and drag as well.

What is a secondary function of the compressor

To provide bleed air to operate various engine and aircraft components.

Purpose of exit stator veins?

To reduce airflow turbulence after leaving compressor and going into diffuser to get ready for burner. This airflow turbulence reduces efficiency of engine.

Major components of torquemeter assembly?

Torque shaft and reference shaft. Torque shaft is rigidly attached to the compressor and RGB. The reference shaft (outer shaft) is rigidly connected to the torque shaft at the compressor extension shaft. The other end is not rigidly connected. The reference shaft does not twist and therefore provides the reference to the twisting torque shaft.

Gas turbine engines are inefficient at low RPM.

True. Gas turbine engines should've used near max throttle setting. Appropriate for reverse region of command for takeoff and especially landing.

Reduction gear boxes are necessary because you must have high engine RPM to produce power efficiently.

True. Turn high RPM and low torque into low RPM and high torque.

The ——- section is most highly stressed part of engine.

Turbine section Operating at temperatures up to 2500 degrees but centrifugal force of 10000 RPM.

Annular combustion chamber advantages

Uniform heat distribution across face of turbine section. Multiple nozzles introduce fuel, mixed with the incoming air, since the chamber is the only use of burner liner and casing the combustion takes places in one location. BUT thin walls make for need to replace, so limits use to aircraft whose engines re easily accessible and maintained.

Can-annular Combustion Chamber is used on ———- and characterized as ——?

Used on larger, high performance aircraft. Combines the ease of maintenance of the can type with excellent thermodynamics of the annular type.

To solve problem of supersonic plane going subsonic to land, planes may have the variable geometry inlet duct. Which

Utilized mechanical devices such as ramps, wedges, or cones to change the shape of the inlet duct (sounds like is could break)

What type of exhaust nozzle is used on an afterburner equipped aircraft?

Variable exhaust nozzle

Examples of mechanics malfunctions

Variable inlet guide vanes and stator vane (fail to change AOA causing too little or much airflow at low engine speeds. Fuel control unit (FCU) — too much fuel causes excessive burner pressure and a back flow of air into compressor. Too little will cause engine to flame out. Foreign object damage (FOD) rotor blades are damaged Variable exhaust nozzle —-at supersonic speed if this convergent opening is not change to divergent, then a back pressure will he produced. Compressor stall.

In the turbo shaft engine ————— the pressure energy is converted into shaft horsepower.

Virtually all of the

Gross thrust

a measurement of thrust due solely from the velocity of the exhaust gases (STATIONARY - STANDARD DAY - EXHAUST ONLY)

Dual spool axial (aka twin/split spool) flow compressor

adds an additional compressor to increase flexibility and power. High and low pressure compressors. Low pressure spool is in front of high pressures, it will provide the initial pressure increase to airflow arriving from the inlet. Must spin slowly enough to provide an initial pressure increase without excessive velo increase. High pressure compressor located after the low pressure compressor, and provides a further increase to airflow pressure. This comp turned by high pressure turbine. Located forward of the low-pressure turbine, the high pressure turbine will receive more energy from the combustion section. The higher pressure turbine, both because it is smaller and lighter weight, and because the high-pressure turbine is located directly after the burner chamber. This higher speed helps to produce a vacuum, which eases the transition from low to the high pressure compressor.

Optimum cruise level

at ~36,000 ft where temperature stabilizes(less benefit from thrust increase with lower temp)and where thrust available plus low fuel flow and diminished drag combine to provide optimum performance.

Centrifugal flow compressor

impeller, driven by turbine, accelerates air outward toward the diffuser which converts high velocity airflow to high pressure, which then moves to compresor manifold. The inefficiency rules out the use on larger aircraft since higher compression ratios are needed for reduced fuel flow and increased thrust. Best for small aircraft with small engines, this is where simplicity, ruggedness and operational flexibility are more important than the ability to handle high rates of airflow.

Axial-centrifugal flow compressor

main advantage = the large pressure increase yet small size that is useful on helicopters and small aircraft

Adiabatic (compressor & turbine)"hopefully the turbine"

no heat exchange (entering or leaving system).

Remedy and Recovery from a compressor stall

reduce attitude of the aircraft and retard PCL

Single-entrance inlet duct

the simplest and most effective inlet duct design - located directly in front of the engine (long, and may result in slight pressure loss BUT has smooth airflow characteristics)

Net thrust

thrust that corrects for the effect of inlet airflow velocity